Selective substitution
of μ-SO<sub>2</sub><sup>2–</sup> groups by either O<sup>2–</sup> or Se<sup>2–</sup> ions occurs upon heating
the bioctahedral rhenium cluster complex K<sub>6</sub>[Re<sub>12</sub>CS<sub>14</sub>(μ-SO<sub>2</sub>)<sub>3</sub>(CN)<sub>6</sub>] in air atmosphere or in the presence of a Se source, respectively,
manifesting the remarkable lability of SO<sub>2</sub><sup>2–</sup> ligands bound to a transition-metal cluster. A series of compounds
based on the new mixed-ligand anions, [Re<sub>12</sub>CS<sub>14</sub>(μ-O)<sub>3</sub>(CN)<sub>6</sub>]<sup>6–</sup>, [Re<sub>12</sub>CS<sub>14</sub>(μ-Se)<sub>3</sub>(CN)<sub>6</sub>]<sup>6–</sup>, and [Re<sub>12</sub>CS<sub>14</sub>(μ-O)<sub>3</sub>(OH)<sub>6</sub>]<sup>6–</sup>, were isolated and their
solid-state structures were elucidated by single-crystal X-ray diffraction
analysis. Along with the previously reported μ-sulfide clusters,
the new species constitute a series of rhenium anionic complexes with
the common formula [Re<sub>12</sub>CS<sub>14</sub>(μ-Q)<sub>3</sub>L<sub>6</sub>]<sup>6–</sup> (Q = O, S, Se, L = CN<sup>–</sup>; Q = O, S, L = OH<sup>–</sup>), within which
the total charge and number of cluster valence electrons (CVEs) are
constant. The article presents insights into the mechanistic and synthetic
aspects of the substitution process, and it comprehensively discusses
the influence of inner ligand environment on the structure, spectroscopic
characteristics, and electrochemical behavior of the novel compounds.